The invention relates to a bootstrap voltage reference circuit which utilizes an n-type negative resistance device.
Two types of n-type negative resistance devices (NNRD) have been tested for use in voltage reference circuits. The p-n junction tunnel diode (TD) and the resonant tunneling diode (RTD). Each of these devices has a local maximum in their respective I-V characteristics which can in principle be used in two ways to develop a reference signal. As a current source using a fixed bias voltage and as a voltage source, by referencing the position of the peak voltage.
The use of n-type negative resistance (NNRD) devices for precision reference sources was initially introduced in U.S. Pat. No. 5,099,191 issued to Galler et al., and incorporated herein by reference. The technique is illustrated in FIG. 1, where an I-V curve 10 for an NNRD (in the illustrated case a p-n junction tunnel diode) is shown biased at slightly to the right of the current peak 12, at an operating point 14 where the DC dynamic resistance (R.sub.dyn) of the matched device is large in magnitude (perhaps 10.sup.3 ohms or more) and negative in sign. Given a bias voltage of modest stability, the fluctuations in the current can be made arbitrarily small by choosing the operating point to be closer to the peak, where R.sub.dyn approaches .infin. and the slope 16 of the I-V curve approaches zero. By exploiting the relative immunity of the current to fluctuations in bias voltage, and converting the current to a voltage, a stable reference is obtained.